Each cytoplasmic organelle of a eukaryotic cell must divide and segregate into the daugther cells during the cell division cycle. We propose biochemical, cytological, and genetic approaches to illuminate the mechanisms of this process, using the vacuole (lysosome) of yeast as a model. We have observed that even the smallest yeast bud contains a single small vacuole, and that the vacuole grows in size as the bud grows. The parent cell vacuole does not grow during the cell cycle. These observations suggest a highly regulated mechanism of vacuole growth in the bud. Through the proposed studies, we hope to understand how organelle division is achieved, how it is regulated by the cell cycle, and how organelles can interact with the cytoskeleton to achieve orderly spatial segregation.